The present invention relates to a method of producing optical images on metallic films and more particularly to a method of producing optical images on chromium or aluminum films.
Heretofore methods of producing optical images on metallic films have involved the use of a photoresist. A photoresist is applied on a metallic film; the photoresist is exposed to a light pattern and is then developed. The development process selectively removes portions of the photoresist to expose the underlying metal. The metal can then be etched by dipping it in an appropriate etchant.
Direct one-step photo-etching method, without the use of a photoresist, has also been accomplished. A source of intense light, such as a laser, is used to selectively etch the metallic film directly. The light source must be of such intensity that evaporation of the metallic film is accomplished upon exposure to the light source.
A latent image is produced on a metallic film having at least one layer of chromium or aluminum by exposing the film to a light pattern, produced by a light source, having an energy intensity level below the threshold for evaporation of the metallic film. The latent image is developed by dipping the metallic film in an etchant.